Glastonbury organisers insist they can't reveal the festival's final headline act until May due to ''contractual reasons.''

Festival boss Michael Eavis has already confirmed Arcade Fire and Kasabian to play on Friday, June 27 and Sunday, June 29 but his daughter Emily insists they can't announce the Saturday headliner until next month.

When asked about the final name, she told BBC 6 Music: ''We can't give you that yet. We're under ... It's just for contractual reasons, but it'll be with you soon. We've got it all booked, it was all confirmed a couple of weeks ago. It's purely that we can't give it to you yet. The full line-up, the thousands and thousands of acts playing across the hundreds of stages, will be with you in May. This is just 80 or 90 bands, a few hand-picked to give you a taster.''

The festival line-up at Worthy Farm this year also includes Lily Allen, Lana Del Rey, Blondie, Robert Plant and Jack White.

Emily also hinted that the former White Stripes hitmaker will not be appearing at any other UK festivals other than Glastonbury.

She said: ''Getting Jack White was a really big deal for us. He's got a history here that goes way back and obviously he's had some brilliant moments here across all the stages.

''When he said he wanted to play here and didn't want to do any other UK festivals, we were really excited. Having him here on a big Pyramid [stage] slot will be just right - he's obviously got all the songs.''